Field of Invention
The present invention relates to a technical field of oil and gas coring equipment manufacture, and more particularly to a WD (while-drilling) sidewall coring tool for oil drilling and coring, which is also suitable for coring a drilled stratum.
Description of Related Arts
In conventional technologies, such as Chinese patent CN 2144707, published Oct. 27, 1993, a rope retrieving type continuous coring tool is disclosed, wherein a conical cylinder device is connected to a bottom end of an inner cylinder of an inner cylinder assembly. A rotating assembly, a locking assembly forming a self-locking structure with an outer cylinder, and a retrieving device are connected to the inner cylinder from bottom to top. According to the present invention, a drill is only tripped once for continuous coring. With the continuous coring tool, drilling time and drilling cost are saved, labor intensity of workers is reduced, coring efficiency is improved, coring depth is increased, and exploration efficiency is improved. However, the conventional coring technologies, as represented by the above patent, still have the following disadvantages: coring is not able to be provided in drilled well sections, and stratum information of the drilled but not cored well section in a borehole is not able to be obtained.
For the above situation, Chinese patent CN2246710, published Feb. 5, 1997, discloses a drilling type sidewall coring tool, which belongs to a field of petroleum logging devices. The drilling type sidewall coring tool comprises a down part and a ground equipment. The down part comprises a mechanical node, an electronic node, and a cable connector. The ground equipment comprises a console, a boosting power, a switchboard, and a collecting ring. The coring tool adopts a double pushing structure, in such a manner that the coring tool firmly presses against a sidewall when coring. A motor is double-phase supplied, and no phase-shifting capacitor is needed, which improves reliability of the system. A convex body is detachably mounted on a shell of a hydraulic motor, wherein the hydraulic motor has a blade type inner structure, and a blade is supported by a supporting ring for closely pressing against an inner surface of a stator, so as to meet working requirements.
Although the conventional sidewall coring technologies, as represented by the above patents, are able to core a drilled well section, the drilling tool should be tripped before coring, and the conventional sidewall coring technologies are not able to provide WD sidewall coring. In addition, coring technique is not mature enough in the world. Therefore, cored volume is small, and quality is not good enough, which influences effectiveness of core analysis.